Can I amend a return to reallocate a Form 8962 credit from prior years?

I got married in 2018 and I'm doing my wife's taxes for the first time. The IRS sent my wife a letter asking for Form 1095-A and a filled Form 8962 related to taxes in 2017. She lived with her parents during 2017 and they shared the healthcare plan but filed separately. After taking a look at my wife's and her parents' tax returns for 2017 I noticed the tax preparer (an older lady who plugs numbers in a tax software without a second look)allocated the entire healthcare credit in Form 8962 to her parents' return which gave them a credit of around $600. However I calculated that if the credit was fully allocated to my wife it would be around $2,500 due to her extremely low AGI/contribution. Can/Should I file amended returns to reallocate the credit from her parents' tax return to my wife's? If so, should I also look at 2016 and see if I should amend those as well? Thanks in advance!